Hi, I would like to ask if anyone knows what this whistling sound means, which only occurs when the engine is cold and only at higher RPM and then stops. If the engine is warm the sound does not appear. Now the car is after replacing the alternator belt and tensioner pulley. The problem still persists. I have attached a video where the sound can be heard towards the end. The car has 230,000 km on it. 2.0 TDI 140 kw.
Thank you for any advice

Welcome to briskoda. I’m sorry but I can’t hear anything over the wind roar..

Hello, Thank you. It can be heard in the end of the video (sec. 3).

Ahhhh, right, a sort of hissing/whistling? Does it make the sound when the car is stationary and you Rev the engine?

No, never on idle even when I rev the engine. Only once the car is moving.

I think it may be the alternator belt which slides a bit. Maybe tension is a bit too low.

I would bring it back to garage where it has been replaced to confirm this. It should be a 5mn fix if this is the real cause.

Strange, they just gave me a new one, and told me that everything should be OK...